Purification of diaryl monosulfides



Patented Dec. 14, 1948 PURIFICATION OF DIARYL MONOSULFIDES Everett E, Gilbert, New York, andHoward 1). Segool, Flushing, N. Y., assignors'to Allied.

OFFICE Chemical & Dye Corporation, a corporation of New York No Drawing. Application June 11, 1946, Serial N0. 676,100

This invention relates to purification of diaryl monosulfides.

Diphenyl monosulfide may be produced by reaction of diphenyl sulfone with sulfur at temperatures of the order of 300 to 400 C.; by reacting benzene, sulfur chloride and aluminum chloride as described in Organic Syntheses, vol. 14, pages 36 and 37 (1934) by reacting benzene and sulfur at elevated temperatures, if desired in the presence of aluminum chloride; by reacting benzene and sulfur monochloride in the presence of zinc dust; or by reacting chlorbenzene and aqueous sodium sulfide under heat and pressure; other diaryl monosulfides may be produced in similar manners. The diphenyl monosulfide produced by such processes, however, is in crude form, being dark-colored and malodorous, and generally contains thiophenol and diphenyl disulfide as impurities; such product is not suitable for use for purposes for which pure diphenyl monosulfide is adapted, e. g. as a plasticizer, insecticide or dye intermediate, The Organic Syntheses reference suggests diphenyl monosulfide produced by the process therein described may be purified by digestion with zinc dust and 40% sodium hydroxide; we have found the product obtained by such procedure, however, may not have a satisfactory color. United States Patent 2,102 200 of December 14, 1937, describes a process for deodorizing crude diphenyl monosulfide by treatment with chlorine or other halogens; this process, however, converts the thiophenol impurity to diphenyl disulfide, which is diificult to remove from the desired monosulfide, so that such process does not provide a satisfactory method for purifying a crude diphenyl monosulfide product.

It is an objectof this invention to provide an improved process for purification of crude diaryl monosulfides, particularly diphenyl monosulfide.

In accordance with this invention a crude diaryl monosulfide having an objectionable color and odor is purified to form a substantially colorless and odorless product free of the corresponding disulfide and thiophenol by subjecting it to the action of a mixture of a metal above hydrogen in the electromotive series and an aqueous solution of an inorganic acid reactable with such metal to yield nascent hydrogen, at a temperature between about 30 and about 100 C., separating the diaryl monosulfide from the mass and then distilling to remove the thiophenol. The product of our process, we have found, fhasv a superior. color to the productobtainedby treatinga crude diaryl monosulfide productwith"'zinc""dust and 8 Claims. (Cl. 260 609) adaptedfor purification of such a product.

aqueous sodium hydroxide. Further, such product is free of the corresponding disulfide. Hence it is evident our process yields products which are substantially purer than products obtained by either of the purification methods suggested by the prior art. 7

The crude diphenyl monosulfide treated in accordance with the preferred embodiment of our invention may be any crude diphenyl, monosulfide having objectionable color and odor, prepared, for example, by reaction of diphenyl sul fonewith sulfur, by reaction of benzene, sulfur, chloride and aluminum chloride or by other suitable methods. Reaction of diphenyl sulfone with sulfur is a particularly effective method for producing. the monosulfide, the reaction being carried out by reacting diphenyl sulfone and sulfur at a temperature of 300 to 400 C. and distilling the diphenyl monosulfide product from the reaction vessel; a typical product prepared by such process has a yellow color and objectionable odor, boils over a 10 C. range and contains about 10% by weight thiophenol and about 5% by weight diphenyl disulfide. 'Our invention is particularly However, our inventionis also useful for purifying crude diphenyl monosulfide obtained by other procedures; for example the product obtained by reacting benzene, sulfur chloride and aluminurn chloride, which typically has a yellow color and objectionable odor. boils over a 15 C. range and contains appreciable amounts of diphenyl disulfide and. thiophenol.

In accordance with our invention the crude diphenyl monosulfide is mixed with a metal above hydrogen in the electromotive series, e. g. iron, zinc, aluminum, magnesium or nickel, and an aqueous solution of an inorganic acid reactabl'e with the metal to yield nascent hydrogenfand the mixture thus'formed subjected to a temperature between about 30 and about 110 C. with strong agitation, whereby nascent hydrogen is evolved. The acid employed may be anystrong inorganic acid such as sulfuric or hydrochloric acid which reacts with the metal to yield nascent hydrogen. The amount of metal admixed with the crude diphenyl monosulfide may vary between about 5% and about 30% by weight thereof, and the amount of acid utilized should be at least 10% in excess of that required to react withthe metal. rying out the purification is to mix the crude diphenyl monosulfide with themetal and with amount of water between 30%1and 70% by. weight-of the crude monosulfide, heat the mix A suitable method of cartemperatures between and about 110 C. with.

agitation.

After the above reaction; isxcom'plete, the re-=v action mixture may be filtered to. remove ,insoluble material therefrom and the. organic layer separated. The organic 1ayer.,-is.thcn. distilled at any convenient pressure to remove thiophenol in the forefraction. A diphenyl monosulfide fraction is next obtained, which is substantially colorless and odorless, boils over a narrow'range of not more than 3 C. and contains no detectable amounts of thiophenol'or diphenyl disulfide.

While the mechanism-of thepurification procedure of ourinvention is not definitely known, it has been observed that hydrogen sulfide is evolved during digestion of the crude .monosulfide with the mixture of metaland acid. It is also believed that the diphenyl disulfidedmpurity .is reduced bythe nascent hydrogen to, thiophenol, which materialcan be readily separated .from the diphenyl monosulfide .by distillation.

The following examples areillustrative of our invention. Amounts are given in parts byweight.

Example 1.- 225 parts of crude diphenyl monosulfide produced by-reaction .of diphenyl sulione and sulfur and havin an. objectionable. color and odor were mixed with 100'parts .ofwater and 50 partsofiron filings and the-mixture was heated to reflux. 295- parts of hydrochloric acid were addedto the refluxing mixture with agitation over. a period 1%.; hours, and refluxing and agitation of .themass were continued for an. additional .hour. The mass was then filtered,v and the organic layer isolated from the filtrate .and distilled-at a pressure of 3 mm. After removal of a thiophenol forefraction, a fraction consisting of 174 parts of a substantially odorless and-colorless.

diphenyl monosulfide product free of diphenyl disulfide and thiophenol and boiling over-a narrow range was obtained.

.-By ;contrast 225 parts of the same crude diphenyl monosulfide-were digested for 1%" hours on a steam bath with 35. parts of -zinc dust and 100 parts of aqueoussodium hydroxide solution, the mass filtered, andthe organic layer separatedfrom the filtrate and distilled to recover diphenyl 'monosulfide; the diphenyl mo ifilsulfide product recovered was yellow, as contrasted with the colorlessproduct.obtained in theabove ex.- ample, and-boiledovera ran e'of 113 to 118 C. at '1 mm.- pressure,

Example 2. -500. parts of crude diphenyl mono sulfideyproduced by reaction of diphenyl sulfone and sulfur and having objectionable color and odor, 200 parts of water and 65parts zinc dust weremixed, the mixture .heated to refluxing and 110.,parts of. 93% sulfuric-acid were gradually added -to the refluxing mixture with agitation over a period of 3 hours. At the end of thistime thereaction mixture was filtered and the organic layer separated from thefiltrate .and distilled. After removalof a thiophenol forefraction, a

colorless, odorlessdiphenyl monosulfide product boiling over a range of 2. C, vand free .of diphenyl disulfide andlthio'phenol was-obtained. I

Examp e 3.--- 298.. parts of crud diphenyl monosulnde. pr duced by. reaction or: diphen l '5 hours. .flltered and the organic layer was recovered from sulfone and sulfur and having objectionable color and odor, 71.6 parts of water and 15.2 parts of iron fillings were mixed and heated on a steam bath at 85 to 95 C. 27.6 parts of 93% sulfuric acid were then added to the mixture with agitation over a 20-minute period, heating and agitationof the massv being continued for an additional At the end of this time the mass was the filtrate and distilled. After removal of a thiophenol, forefraction, 218 parts of a substantially colorless, odorless diphenyl monosulfide product' boiling over a narrow range and free were ] ing out'the above process without departing from the-scope of the invention, it is intended that all. matter contained in the above description shall be interpreted as illustrative and not in a limiting sense. Thus, while the above descrip- 'tion has dealt with purification of diphenyl monosulfide,. it is to beunderstood other crude diaryl monosulfides, .may also. bepurified in the same manner. Forexample, the process ofour invention may be applied to purification of crude aminoaryl or hydroxyarylmonosulfides prepared, for example, by reaction of the corresponding amine or phenol, respectively, with sulfur as described in Chemical Abstracts, vol. 28, page 5052 (1934,); or it may be, applied to purification of crude allgyl, substituted, or halogenated diaryl monosulfides pre ared. for. examp by reaction of the corresponding alkylsubstituted. .or halo" enated aromatichydrocarbon with sulfur m.-

ride' or a substanceigenerating sulfur chloride in the presenceof iron or iron chloride.

We claim:

1. A 7 process ior the purification of crude diphenyl monosl fide of objectionable color and odorto produce a substantially. colorless product boiling over arange of not more than 3 C. which comprises subjectin said. diphenyl monosulfide to the action of a mixture of a metalabove hydro.- gen in the electromotive Seriesand an inorganic acid reactable with said metal to yield nascent hydrogen, at a temperature between. about 30 and-about 0., separating the thus treated diphenyl monosulfide fronrthe' reaction mixture and distilling to remove thiophenol.

2. A process for the purification of crude; diphenyl monosulfide of ,objectionable color and odor pr uc by reaction oidiphenvl sulf n and. sulfur .to produce a. substantially .eolorless oduc boiling over ar ng ofn more han 3"v C, which comprises subjecting said diphenyl monosulfide to the action of a mixture of a metal above h d ogen. in the. electrom tiveseri s and an inorganic acid reactahle with said. metal to d. n s ent hydrog n, at. a, tempera u between about30 andabout 110? C,,.separating the thus treated diphenyl monosulfide from the reaction mixture and'distilling 0 remove thiophenol.

3. A- process for the purification of crude, diphenyl monosulfide of objectionable color and odor to-produce a substantiallycolorless product, boiling over a range of not more than 3 C. which comprises mixing saiddiphenyl monosulfide with water and an amount of a metal above hydrogen in the electromotive.[series between about 5% and about 30% by weight of said sulfide, heating the mixture to a temperaturebetween about 30 and abo t 1 090.. radually addin to the heated i ur with agitationian inorg nic. acid re actable withssaid metaltosield nascent. hyd ogen,

5 separating the thus treated diphenyl monosulfide from the reaction mixture and distilling said sulfide to remove thiophenol.

4. A process for the purification of crude diphenyl monosulfide of objectionable color and odor to produce a substantially colorless product, boiling over a'range of not more than 3 C., which comprises subjecting said crude diphenyl monosulfide to the action of a mixture of iron and an inorganic acid reactable therewith to yield nascent hydrogen, at a temperature between about 30 and about 110 0., separating the thus treated diphenyl monosulfide and distilling said sulfide to remove thiophenol. i

5. A process for the purificationf'oi crude diphenyl monosulfide of objectionable 'color -zand odor to produce a substantially colorless product, boiling over a range of not more than3 C., which comprises subjecting said crude diphenyl monosulfide to the action of a mixture of zinc and an inorganic acid reactable therewith to yield nascent hydrogen, at a temperature between about 30 and about 110 0., separating the thus treated diphenyl monosulfide and distilling said sulfide to remove thiophenol.

6. A process for the purification of crude diphenyl monosulfide of objectionable color and odor to produce a substantially colorless product, boiling over a range of not more than 3 C., which comprises subjecting said crude diphenyl monosulfide to the action of a mixture of iron and sulfuric acid at a temperature between about 30 and about 110 C., separating the thus treated diphenyl monosulfide and distilling said sulfide to remove thiophenol.

7, A process for the purification of crude diphenyl monosulfide of objectionable color and odor to produce a substantially colorless product, boiling over a range of not more than 3 C., which comprises subjecting said crude diphenyl monosulfide to the action of a mixture of zinc and sulfuric acid at a temperature between about 30 and about 110 C., separating the thus treated diphenyl monosulfide and distilling said sulfide to remove thiophenol.

8. A process for the purification of crude diphenyl monosulfide of objectionable color and odor to produce a substantially colorless product, boiling over a range of not more than 3 C., which comprises subjecting said crude diphenyl monosulfide to the action of a mixture of iron and hydrochloric acid at a temperature between about 30 and about 110 (3., separating the thus treated diphenyl monosulfide and distilling said sulfide to remove thiophenol.

EVERETT E. GILBERT. HOWARD D. SEGOOL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Blair et a1 Oct. 31, 1933 OTHER REFERENCES Number 35 119, page 149 (18 61).

Certificate of Correction Patent No. 2,456,500.

December 14, 1948. EVERETT E. It is hereby certifie d that errors appear in the printed specifi numbered patent requiri g correction as follows: 7

Column 1, line 29, for "2,102 200 read 2,102,200; line 50, for 100 0. 110 0. column 4, line 3 for the Word filling s read filings; e same may conform to the Signed and sealed this 29th day of M GILBERT ET AL.

cation of the above read arch, A. D. 1949.

THOMAS F. MURPHY,

Assistant aommissioner of Patents. 

